1. Field of the Invention
The present invention relates to an engine-operated generator unit covered by a soundproof case in its entirety.
2. Discussion of Related Art
The engine-operated generator in which an engine and a generator driven by the engine are integrated as a portable unit is used at a construction work site generally. And in consideration of influences to the surroundings when it is operated in a city area especially at night, an engine-operated generator covered by a soundproof case in its entirety has been used widely in order to restrain operation noise to as low a level as possible.
In this kind of engine-operated generator unit, openings for inhaling or discharging air are made few in number and small in size to achieve necessary low noise level during operation. But on the one hand, it is necessary to devote great care to cooling the interior of the soundproof case because the area of the openings is small.
Japanese Utility Model Publication No. 64-3777 discloses an engine-operated generator in which an engine and a muffler are covered by a duct to be isolated from other instruments and cooling air is forcibly passed through the duct and discharged at the side of the muffler out of the soundproof case so that the high temperature properly discharged and cooling air is prevented from recirculating into the soundproof case.
However, as for a generator placed outside of the duct in the soundproof case, it is necessary to provide another cooling air passage besides the above duct or an exclusive cooling fan for the generator, and therefore the engine-operated generator is caused to be large-sized.
In the engine-operated generator of the Japanese Utility Model Publication No. 64-3777, a fan for cooling the generator is provided separately from a cooling fan for forcibly ventilating the duct covering the engine and the muffler, and air discharged from the fan for cooling the generator is joined in the duct after cooling the generator. Therefore, passages of air are complicated, there are two fan noise sources, and the apparatus is caused to be large-sized owing to installing two fans.